JPS6130031B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for plating polyester resin. More specifically, the present invention relates to a plating method that imparts an excellent metallic appearance to the surface of a thermoplastic polyester resin without impairing its physical or chemical properties. Thermoplastic polyester resins, such as polyester terephthalate resins, have excellent mechanical properties and chemical resistance, and are used as engineering plastics in various electrical and mechanical parts. Metal plated products are expected to be applied to new fields that require heat resistance and mechanical strength that were not available with conventional ABS resin or polypropylene resin plated products. In general, plastic plating consists of the following steps: (1) pretreatment, (2) chemical etching, sensitizing, (4) activating, (5) chemical plating, and (6) electroplating, depending on the type of plastic. Various methods have been used. For example, in the case of ABS resin, the pretreatment process (1) aims to remove oils and fats from the molded product, and the subsequent chemical etching process (2) uses an oxidizing acid solution such as chromic acid-sulfuric acid to roughen the surface. After passing through the steps (3), (4), and (5) above, a finished plated product with excellent adhesion can be obtained. On the other hand, since polyester resin is relatively stable against acidic liquids, surface roughening is insufficient even when treated with the above-mentioned chromic acid-sulfuric acid mixture.
Even after the subsequent plating process, sufficient adhesion strength with metal cannot be obtained. When an alkaline solution is used as the etching solution, surface roughening progresses. This is thought to be because the surface of the polyester resin undergoes hydrolysis in the alkaline solution and partially dissolves in the etching solution. However, although this alkaline solution treatment somewhat improves the adhesion of the polyester resin to the plating metal coating, the effect is extremely small and poses a considerable problem in practical use, and the loss of gloss on the metal surface is inevitable. The present inventors aimed to improve the physical properties of polyester resin in order to improve the problems of polyester plating.
As a result of intensive research on improving chemical properties and etching conditions, we found that by mixing a specific amount of alkaline earth metal carbonate with thermoplastic polyester, properties that are extremely suitable for plating are developed, and surface roughening can be easily prevented. In addition, the excellent properties of polyester resin such as mechanical properties, thermal properties,
The present invention was achieved based on the finding that chemical properties etc. are improved. That is, the present invention provides a method for plating with a polyester resin, in which 3 to 100 parts by weight of an alkaline earth metal carbonate (excluding calcium carbonate) with an average particle size of 20 μm or less per 100 parts by weight of thermoplastic polyester is used as the polyester resin. A method for plating a polyester resin, which uses a polyester resin containing 0 to 100 parts by weight of a fibrous reinforcing material, and which is characterized in that the polyester resin is previously brought into contact with an alkaline solution and then brought into contact with an acidic solution. It is. In the present invention, thermoplastic polyester includes terephthalic acid, isophthalic acid,
2 such as naphthalene-2,6-dicarboxylic acid, etc.
Using basic acids or their ester-forming derivatives, ethylene glycol,
Using glycols such as propylene glycol, butylene glycol, neopentyl glycol, 2,2,4,4-tetramethylcyclobutanediol, 4,4'-isopropylidene-di-p-phenyl, etc. or ester-forming derivatives thereof. It is a homopolymer or copolymer polymerized by Particularly preferred polyesters include aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polybutylene-2,6-naphthalate, etc., but these polyesters can be partially copolymerized with other copolymers. Optionally substituted with other components. Thermoplastic polyester can be obtained by conventional manufacturing methods. Further, its intrinsic viscosity is preferably 0.3 or more, more preferably 0.5 or more. In addition, in the present invention, the alkaline earth metal carbonate contained in the thermoplastic polyester is
Examples include ZnCO ₃ , BaCO ₃ , MgCO ₃ and the like. The amount added is 3 to 100 parts by weight, particularly preferably 5 to 60 parts by weight, per 100 parts by weight of the thermoplastic polyester.
Parts by weight. At less than 3 parts by weight, the effect of the addition of the alkaline earth metal carbonate is not significant, and
If it exceeds 100 parts by weight, the strength (especially impact strength) of the molded product will decrease, and the appearance of the plated product will also be poor, which is not preferable. Further, the particle size of the alkaline earth metal carbonate is on average 20μ or less, preferably 5μ or less. In other words, if the average particle size is larger than 20μ, over-etching is likely to occur during etching in the plating process.
This is not preferable because not only the metallic luster is lost but also the adhesion is reduced. Typical examples of the fibrous reinforcing materials used in the present invention include glass fibers, carbon fibers, and asbestos fibers. The amount of these additives is preferably 5 to 100 parts by weight per 100 parts by weight of the thermoplastic polyester. If the amount of the fibrous reinforcing material added exceeds 100 parts by weight, the mechanical rigidity tends to improve, but it is not preferable because it becomes difficult to manufacture and mold the polyester composition and the appearance of the finished plated product becomes unfavorable. . Various methods can be used to blend the above-mentioned fibrous reinforcing material and alkaline earth metal carbonate into the thermoplastic polyester, but it is preferable to use a melt-kneading method using an extruder to uniformly knead and disperse the above-mentioned fibrous reinforcing material and alkaline earth metal carbonate prior to molding. It is desirable to In the present invention, additives other than the above, such as colorants, nucleating agents, blowing agents, flame retardants, stabilizers, fillers, etc., may be added to the thermoplastic polyester for the purpose of improving various other properties. It doesn't matter as long as it doesn't reduce the effect. In the present invention, thermoplastic polyester is plated with a polyester resin mixed with a predetermined amount of alkaline earth metal carbonate and, if necessary, a fibrous reinforcing material. Perform etching process. A relatively wide range of conditions can be adopted as the alkali treatment conditions for this etching (surface roughening), but considering the adhesion of the polyester composition to the plating metal coating and the appearance of the plating molded product, the following conditions are possible: It is desirable that the condition satisfies the formula. 15000C・2(T-20/10)・t20 [However, C, t and T in the formula are as follows. C: equivalent concentration of alkaline solution (normative),
t: treatment time (minutes), T: treatment temperature (° C.)] Preferably, the following conditions are satisfied. 0.1C10, 20T80 1t40 Further, the acidic solution used subsequent to the alkali treatment is an acidic aqueous solution with a pH of 6 or less. Although the treatment time is arbitrary, 5 minutes to 1 hour is usually sufficient. The alkaline components of the above alkaline aqueous solution are:
Examples include alkali metal or alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide. Among these, sodium hydroxide, potassium hydroxide, and particularly sodium hydroxide are preferred. Examples of the acid component of the acidic aqueous solution include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid. Among these, hydrochloric acid is particularly preferred. After the above-mentioned alkaline solution treatment and acidic solution treatment, the plating operation is completed through processes such as sensitizing, activating, chemical plating, and electroplating, which are widely used for plastics. This operation can be performed under normal conditions. According to the method of the present invention, a metal coating with excellent adhesiveness can be formed on the surface of a polyester resin, especially a molded product thereof, and there is no deterioration of various properties of the polyester resin, such as mechanical properties and thermal properties, due to the plating operation. , a plated product with excellent physical properties can be obtained. The present invention will be specifically explained below with reference to Examples. Of the measurement items used in this example, bending strength, impact strength, and heat distortion temperature were measured individually.
It was carried out according to ASTMD-790, D-256 and D-648, and the intrinsic viscosity of the polyester was measured at 35°C using orthochlorophenol solvent. Example 1 20 parts by weight of barium carbonate with an average particle size of 0.5μ and 0, 20, 50 or 100 parts by weight of glass fiber were added to 100 parts by weight of polyethylene terephthalate having an intrinsic viscosity of 0.73, which had been previously dried with hot air at 120°C for 5 hours. After adding and mixing in a tumbler, they were melt-mixed using a 65 mmφ extruder at a cylinder temperature of 280°C, and the threads coming out of the die were cooled and cut to obtain pellets for molding. Using this pellet, a 5-ounce injection molding machine was used at a cylinder temperature of 280℃, an injection pressure of 800Kg/cm ² , a mold temperature of 140℃, and a molding cycle.
The test molded product was injection molded for 45 seconds. The bending breaking strength and heat deformation temperature of the injection molded product obtained were as shown in Table 1. In addition, this injection molded product was immersed in a 5N aqueous sodium hydroxide solution at 50℃ for 20 minutes, then immersed in a 5% hydrochloric acid aqueous solution at 23℃ for 5 minutes, and electroplated with copper according to the conventional method shown below. was applied. (1) Sensitizing The surface roughened molded product is treated with stannous chloride 20
g, 10 c.c. of hydrochloric acid (38% aqueous solution) and 1000 c.c. of water for 3 to 5 minutes at room temperature. (2) Washing with water: Wash under running water for 1 to 2 minutes. (3) Activation Immerse in a mixture of 0.5g palladium chloride (38% aqueous solution) 5c.c. and water 1000c.c. for 2 to 5 minutes at room temperature. (4) Washing with water: Wash under running water for 1 to 2 minutes. (5) Chemical nickel sulfate PH8-9 with a composition consisting of nickel sulfate 20g/, sodium hypophosphite 15g/, ammonium sulfate 50g/, and sodium citrate 20g/
Immerse in the solution for 10 minutes at 40-50℃. (6) Washing with water: Wash under running water for 1 to 2 minutes. (7) Electrolytic copper plating A current of 3 A/dm ² was applied at a temperature of 25 to 30°C in an aqueous solution consisting of 220 g of copper sulfate, 50 g of sulfuric acid, and 5 g of brightener #1 (product of Ebara Eudylite Co., Ltd.). Flow for ~60 minutes to form a plating film with a thickness of about 40 μm on the resin molded product. The film adhesion strength of the plated molded product obtained through the above treatment steps was measured and is shown in Table 1.

[Table] From Table 1, it can be seen that the plated products maintain an excellent appearance, and as the amount of glass fiber increases, the impact strength and heat distortion temperature tend to increase. Comparative example 1 Without adding barium carbonate and reducing the amount of glass fiber
A molded article and copper plating were obtained in the same manner as in Example 1 except that the amount was 30 parts by weight. The bending strength, heat deformation temperature, and adhesion strength of the plated product of this molded product were as follows. Bending strength 1950Kg/m ² Heat distortion temperature 233℃ Adhesion strength of plating film 0.5Kg/cm Example 2 Polybutylene terephthalate with intrinsic viscosity 0.82
After adding and mixing 30 parts by weight of glass fiber and 20 parts by weight of magnesium carbonate having an average particle size of 0.5 μm to 100 parts by weight, the mixture was melt-mixed in an extruder to prepare pellets for molding. This pellet was injection molded at a cylinder temperature of 260°C, an injection pressure of 800 kg/cm ² and a mold temperature of 60°C to prepare a test piece for plating. Using this test piece, etching treatment was carried out with various alkaline aqueous solutions shown in Table 2, and subsequent treatment steps with acidic solution were carried out in the same manner as in Example 1 to obtain copper-plated molded articles. The film adhesion strength of this plated molded product was as shown in Table 2.

【table】

[Table] From Table 2, the effect of alkaline aqueous solution treatment is clear. In all of the above examples, the samples were immersed in an aqueous hydrochloric acid solution having a pH of 6 or less after the alkali treatment. When the samples were not immersed in an aqueous hydrochloric acid solution, the more advanced the alkali treatment, the less glossy the appearance tended to be.

Claims (1)

[Claims] 1. In a method of plating a polyester resin, the polyester resin contains 3 to 100 parts by weight of an average particle size of 20 μm per 100 parts by weight of thermoplastic polyester.
A polyester resin containing the following alkaline earth metal carbonates (excluding calcium carbonate) and 0 to 100 parts by weight of a fibrous reinforcing material is used, and the polyester resin is previously brought into contact with an alkaline solution. A method for plating polyester resin, which is characterized in that it is then subjected to contact treatment with an acidic solution. 2. The method of claim 1, wherein the polyester resin contains 5 to 100 parts by weight of fibrous reinforcement per 100 parts by weight of thermoplastic polyester.